The present application claims the priority of the commonly owned copending German patent application Serial. No. 100 28 000.5 filed Jun. 8, 2000. The disclosure of the above-referenced German patent application, as well as that of each US and foreign patent and patent application identified in the specification of the present application, is incorporated herein by reference.
The invention relates to improvements in methods of and in apparatus for applying an adhesive substance, such as a hotmelt, to selected portions or sections of one side of a running web or strip of paper or other wrapping material in a machine wherein the web is converted into a continuous or discontinuous tubular wrapper or envelope surrounding a rod-shaped filler. A presently preferred application of the improved method is in machines which are designed to turn out filter mouthpieces for tobacco stoke, filter cigarettes, plain cigarettes and similar rod-shaped smokers"" products.
It is customary to provide a web of cigarette paper or so-called tipping paper (sections of a web consisting of tipping paper are provided with longitudinally spaced-apart patterns of perforations for admission of atmospheric air into the tobacco smoke flowing from the lighted end of a filter cigarette, cigar or cigarillo to the mouth of the smoker) with films or layers of a suitable adhesive which bonds the marginal portions of a tube into a customary seam extending lengthwise of the smokers"" product. The adhesive can also serve to bond the converted (finite) length of the web to the fragments of tobacco and/or to the normally fibrous filter material for tobacco smoke. The leader of the web is repeatedly severed upon completion of the application of adhesive to non-perforated portions of the leader to yield uniting bands which are convoluted around a filter mouthpiece and around the adjacent end portion(s) of one or two filter cigarettes to form therewith a filter cigarette of unit length or a filter cigarette of double unit length.
It is also known to provide a filter cigarette making machine (also called tipping machine) with a sensor which monitors the positions of adhesive patterns and generates signals serving to carry out or to initiate certain adjustments of the detected positions of the patterns of perforations (or of inidicia or markers denoting the positions of such patterns and being applied to the running webs) when the monitored positions; depart from the desired or preselected or required or optimum positions. Reference may be had to U.S. Pat. No. 5,735,292 (granted Apr. 7, 1998 to Draghetti for xe2x80x9cMETHOD AND DEVICE FOR THE PRODUCTION OF FILTER TIP BANDS FOR VENTILATED CIGARETTESxe2x80x9d) which describes and shows an apparatus for and discloses a method of applying adhesive films to non-perforated portions of running webs of tipping paper for use in filter cigarette making machines.
The patent to Draghetti discloses two embodiments of the aforesaid method. Each embodiment provides for a monitoring of the relationship between the angular position of a rotary drum-shaped adhesive applicator and the angular position of a rotary carrier for the knife or knives serving to sever the leader of the web upon completion of the application of adhesive to the foremost (not yet separated) uniting band. Any departures of the location of detected perforated zone from the desired or required location are compensated for by changing the angular position of the rotary knife carrier and/or by changing the extent of movement of the web between the adhesive applicator and the severing unit.
A drawback of the just discussed proposal of Draghetti is that a correction of the positions of adhesive-coated section relative to the locations of cuts across the web necessitates a change of the positions of adhesive-coated sections relative to the perforated patterns and vice versa. This involves the utilization of additional sensor means and the utilization of one or more additional control unit or units for the processing of signals being transmitted by additional sensors with attendant additional costs and increased space requirements of the patented apparatus, Furthermore, the patent to Draghetti does not, describe and/or illustrate such additional equipment including the sensor or sensors and the control circuits which would be capable of processing the signals furnished by the additional sensor(s). Therefore, and to the best of applicants"" knowledge and belief, the patented proposal has failed to gain widespread acceptance in the tobacco processing industry.
An object of the present invention is to provide a novel and improved method which is not only simpler but also more reliable than heretofore known methods in that it facilitates the establishment of a long-lasting optimum relationship between the perforated pattern or patterns and the adhesive-coated portion or portions of each of a short or long series of uniting bands.
Another object of the invention is to provide a method which renders it possible to operate with a single control unit for signals being supplied by the sensors for various parameters requiring consideration in connection with the application of adhesive to uniting bands for use in filter cigarette making and analogous machines employing filter mouthpieces having tubular envelopes provided with patterns of perforation for the admission of atmospheric air.
A further object of the instant invention is to provide a method which can be practiced by resorting to apparatus employing novel combinations of available components.
An additional object of the invention is to provide a novel and improved apparatus for the practice of the above outlined method.
Still another object of the invention is to provide an apparatus which can be installed in existing filter tipping machines and other machines for the processing of running webs which are made of paper or the like and must exhibit accurately distributed adhesive bearing sections and uncoated sections.
A further object of this invention is to provide a filter tipping machine which embodies the above outlined apparatus.
Another object of the present invention is to provide novel and improved filter cigarettes or analogous smokers"" products.
An additional object of the invention is to provide a novel and improved combination of adhesive applying, conveying, severing ad synchronizing means for use in filter tipping machines.
One feature of the present invention resides in the provision of a method of manipulating an elongated web of wrapping material (such as a web of tipping paper of the character utilized in many filter cigarette making machines) having a succession of longitudinally spaced-apart first sections (such first sections can be perforated, either entirely or in part) separated from each other by successive second sections which are to be at least partially coated with a flowable substance (such as a hotmelt or another suitable adhesive substance). The improved method comprises the steps of advancing the web lengthwise in a predetermined direction, along a predetermined path and at a predetermined speed, monitoring at least one first portion of the path and generating first signals at a first frequency denoting the detection of successive first sections, severing the web across successive second sections of the web in a second portion of the path downstream of (i.e., following) the first portion of the path to thus convert the web into a series of successive bands having predetermined lengths, scanning a third portion of the path downstream of the first portion to detect successive bands and generating a series of second signals at the frequency of detection of successive bands, comparing the first signals with the second signals to detect differences (if any) between the phases and/or other characteristics of the first and second signals, and temporarily altering the speed of the web when the comparing step indicates a phase difference exceeding a predetermined value,
The improved method further comprises the steps of applying a flowable substance to successive second sections of the web in a fourth portion of the path downstream of the at least one first portion, and maintaining the first and fourth portions of the path at a fixed distance from each other.
The method can further comprise the step of ascertaining the spacing of successive first sections of the web from each other (this can take place in the at least one first portion of the path); the altering step of such method can be carried out when the spacing of successive first sections of the web from each other departs from a preselected value. This method can further comprise the step of ascertaining the speed of the web simultaneously with each ascertainment of the spacing of successive first sections of the web from each other.
The improved method can further comprise the step of applying flowable substance to successive second sections of the web following (i.e., subsequent to) the monitoring step and in a fourth portion of the path at a fixed distance from the second portion of the path. The just outlined method can further comprise the steps of generating third signals at a frequency corresponding to that of applying flowable substance to successive second sections, comparing the positions of phase of third signals only with the positions of phases of the second signals to ascertain the presence or absence of differences between the phases of the second and third signals, and temporarily altering the frequency of application of flowable substance to successive second sections of the web when the difference between the phases of the second and third signals departs from a preselected value,
The advancing step can include entraining the web by the peripheral surface of at least one rotary advancing member (such as a roller which defines with a second roller a nip for the web): the step of temporarily altering the speed of the web can include changing the speed of the peripheral surface of the at least one advancing member.
The predetermined value can include or embrace a range of acceptable tolerances of differences between the phases of the first and second signals.
The method can further comprise the step of varying the distance between the first sections of the web in the at least one first portion and the second portion of the path in dependency upon detection of changes of the predetermined speed.
Another feature of the present invention resides in the provision of an apparatus for supplying a series of discrete perforated uniting bands of tipping material to a filter cigarette making machine. The improved apparatus comprises means for advancingxe2x80x94in a predetermined direction and along a predetermined pathxe2x80x94an elongated web which consists (at least in part) of tipping paper and is provided with a series of at least partially perforated first sections which alternate with non-perforated second sections, means for applying a flowable adhesive to successive second sections of the web in a first portion of the path, means for severing the web across successive second sections in a second portion of the path downstream of the first portion to thus convert the web into a succession of discrete uniting bands, at least one first sensor which is adjacent a third portion of the path upstream of the second portion and is arranged to generate first signals denoting detection of successive first sections of the running web, at least one second sensor which is arranged to monitor the frequency of severing of the web in the second portion of the path, control means including a suitable circuit or other means for comparing the first signals with the second signals, and means for temporarily altering the speed of advancement of the web when the comparison of first and second signals reveals the presence or existence of deviations outside of a predetermined (acceptable) range.
The first and second portions of the path (i.e., the locations of the adhesive applying means and the severing means) can be disposed at a fixed distance from each other (as seen in the direction of advancement of the web along its path).
The improved apparatus can further comprise means for ascertaining the distances between successive first sections of the web and means for comparing the thus ascertained distances with a reference distance. The altering means of such apparatus is or can be arranged to temporarily alter the speed of advancement of the web in dependency upon the extent of departure of the ascertained distance from the reference distance. The means for ascertaining the distances can form part of one of the first and second sensors (such as the first sensor). The means for comparing the ascertained distances can form part of the aforementioned control means.
The third portion of the path can be located at a first fixed distance from and downstream of the first portion of the path and at a second fixed distance from and upstream of the second portion of the path.
The advancing means can comprise at least one roll or an analogous rotary advancing member having a peripheral surface which is arranged to contact and entrain the web in the predetermined direction, and the means for temporarily altering the speed of advancement of the web can include means (such as a variable-speed electric motor) for varying the peripheral speed of the at least one roll in response to appropriate signals from the control means.
The apparatus can further comprise at least one third sensor which is arranged to generate third signals denoting the frequency of application of flowable adhesive to successive second sections of the running web, means for comparing the third signals with the first and/or second signals, and means for temporarily altering the frequency of application of adhesive to the second sections of the running web when the comparison of the third signals with the first and/or second signals reveals the need for a change of the frequency of adhesive application. The aforementioned comparing means can form part of the control means or can constitute a discrete control means. In many instances, the first mentioned control means can include means for comparing the first signals only with the second signals.
The third sensor can be disposed in or at a portion of the path between the first and second portions of such path.
The first and/or second and/or third sensor can constitute a photoelectric detector or a proximity detector.
The novel features which are considered as being characteristic of the present invention are set forth in particular in the appended claims. The improved apparatus itself, however, both as to its construction and the modes of assembling, installing and operating the same, together with numerous additional important and advantageous features and attributes thereof, will be best understood upon perusal of the following detailed description of certain presently preferred specific embodiments with reference to the accompanying drawings.